Northampton Saints coach Jim Mallinder felt Dylan Hartley could have no defence over his red card in Friday's heavy European Champions Cup defeat to Leinster.
The Saints were beaten 37-10 at Franklin's Gardens, their cause not helped by England captain Hartley getting sent off for swinging an arm into the head of Sean O'Brien in the 58th minute - just six minutes after coming on.
Hartley, who has a long history of disciplinary issues, is likely to face further sanction - with England's 2017 Six Nations campaign to begin on February 4 - and Mallinder made no excuses for the hooker.
"You can't strike to the head. We've seen enough of them over the last few weeks and I think it was a red card," he said.
"Dylan has been playing really well and leading England by example, so it was disappointing on returning from England and doing such a good job that that happens.
"I wouldn't say it cost us the game. I think we started badly, came back into the game pretty well and we had just conceded a try, actually, so we were already a few points down.
"But I think when you go down to 14 men against such a quality side as Leinster then you're always going to be up against it."